A urethane coating film waterproof material is used in a wide range of applications including waterproof materials such as roofs, exterior walls, floors, desk slabs, floor slabs, or pits of various structures including civil engineering and construction, and anticorrosion materials.
The urethane coating film waterproof material is largely divided into a two-component reaction type material obtained by mixing an isocyanate prepolymer (primary material), and a compound (curing material) obtained by adding a plasticizer, a filler, a pigment, and a reaction catalyst to polyol and polyamine to produce a mixture, and stirring and curing the mixture; and a one-component type material obtained by coating a material (primary material) which is obtained by adding a filler which has been dried, a plasticizer, a pigment, a reaction catalyst and a moisture latent curing agent, such as ketimine, and oxazolidine, to an isocyanate prepolymer, and being cured with moisture in the air.
Further, examples of a urethane coating film waterproof material of the two-component reaction type include a type of material which is obtained by adding water into a material (primary material) obtained by adding a filler, a plasticizer, a pigment, a reaction catalyst, and magnesium oxide into an isocyanate prepolymer, stirring and reacting them, and allowing magnesium oxide to adsorb carbon dioxide, which is generated by the reaction.
As a general-purpose two-component reaction type urethane coating film waterproof material, the following two types can be exemplified.
(1) A type of material which is obtained by
preparing tolylene diisocyanate (hereinafter, also abbreviated to as “TDI”)-based prepolymer (primary material) having two or more isocyanate groups by mixing TDI with polypropylene glycol (hereinafter, also abbreviated as “PPG”) having two or more hydroxyl groups, heating, and stirring them;
preparing a curing material by adding PPG having two or more hydroxyl groups, a plasticizer, a filler, a pigment, a solvent, an anti-aging agent, an anti-foaming agent, and a reaction catalyst into aromatic amine, such as 3,3′-dichloro-4,4′-diaminodiphenylmethane (hereinafter, also abbreviated as “MOCA”) having two or more amino groups, and diethyl toluene diamine (hereinafter, also abbreviated as “DETDA”), and
mixing the TDI-based prepolymer and the curing material;
stirring them using a stirrer; and
applying the mixture using a spatula or a roller.
(2) An ultra-fast curing type material which is obtained by
preparing a diphenyl methane diisocyanate (hereinafter, also abbreviated as “MDI”)-based prepolymer having two or more isocyanate groups by mixing MDI having a surplus equivalent ratio with a hydroxyl group equivalent of PPG having two or more hydroxyl groups and reacting the mixture by heating and stirring;
preparing a material (primary material) by adding a plasticizer to the MDI-based prepolymer having two or more isocyanate groups;
preparing a curing material by blending an amine such as DETDA having two or more amino groups and Jeffamine, PPG having two or more hydroxyl groups, a plasticizer, an anti-aging agent, and a reaction catalyst,
preparing a material by adding a pigment in which a plasticizer is added and kneaded in advance to the curing material; and
heating the mixture of the primary material and the material using a dedicated machine, hose-feeding the mixture to be mixed in a tip of a hose, stirring and performing spray coating.
A urethane coating film waterproof material is capable of easily constructing a seamless waterproof layer after curing on a foundation having a complicated shape by performing coating using a trowel or a spatula, roller-coating, or spray-coating at room temperature. Accordingly, the urethane coating film waterproof material is widely used for renovation, repair, and the like of various structures.
Further, performance of a coating film waterproof material for a roof and a coating film waterproof material for an external wall among coating film waterproof materials for architecture is defined in JIS A 6021 “Coating film waterproof material for architecture” of Japanese Industrial Standards (JIS).
In the coating film waterproof material for a roof defined in JIS A 6021 of Japanese Industrial Standards (JIS), there are two kinds of materials, that is, a highly extensible coating film waterproof material (former group 1) and a high-strength coating film waterproof material as urethane rubber-based materials.
The highly extensible coating film waterproof material (former group 1) for a roof is defined in that the tensile strength at 23° C. is 2.3 N/mm2 or greater and the elongation rate at the time of fracturing between marked lines is 450% or greater.
The high-strength coating film waterproof material for a roof is defined in that the tensile strength at 23° C. is 10.0 N/mm2 or greater and the elongation rate at the time of fracturing between marked lines is 200% or greater.
The highly extensible coating film waterproof material (former group 1) for a roof is used for a balcony of a building or rooftop waterproofing as a general-purpose waterproof material. Meanwhile, the high-strength coating film waterproof material for a roof is used in applications for which strength, water resistance, and hot water resistance are required such as a rooftop parking lot, a slate roof, an underground structure, and a rooftop for planting.
As the highly extensible coating film waterproof material (former group 1) among urethane coating film waterproof materials, a coating film waterproof material belonging to the type (1) which is obtained by combining a TDI prepolymer and MOCA (DETDA), mixing and stirring the mixture in a stirrer, and performing coating using a trowel or a spatula or roller coating has been already commercialized. Since this type of coating film waterproof material is used after the weights of a primary material and a curing material are measured using scales to be divided in containers, and mixed and stirred in a stirrer, the ratio of the primary material to the curing material is set to 1:1 or 1:2 in terms of mass such that measurement can be easily performed. The NCO ratio of the primary material which is a reaction component is in the range of about 3.3% to about 3.8%.
In addition, as the high-strength coating film waterproof material among urethane coating film waterproof materials, an ultra-fast curing type coating film waterproof material belonging to the type (2) which is obtained by heating an MDI-based prepolymer and DETDA separately from each other using a dedicated machine, hose-feeding the MDI-based prepolymer and DETDA to be mixed with each other at the tip of a hose, stirring the mixture, and performing spray-coating on the mixture has been commercialized. In this type of coating film waterproof material, since the primary material and the curing material are fed in a hose from a container having a constant volume to a pump to be mixed at the tip of the hose, stirred, and spray-coated on the mixture, the volume ratio of the primary material to the curing agent is set to 1:1. The NCO ratio of the primary material which is a reaction component is 10.0% or greater.
A difference in the NCO amount becomes a difference in crosslinking density. For this reason, the highly extensible coating film waterproof material (former group 1) whose NCO amount is relatively small has a high elongation rate and low strength. The high-strength coating film waterproof material whose NCO ratio is relatively high has strength stronger than that of the highly extensible coating film waterproof material (former group 1) and has a low elongation rate.
As the urethane coating film waterproof material, the above-described highly extensible type coating film waterproof material (former group 1) has been used most for general purposes. However, from designation in group 2 substances (substances causing chronic and late-onset disorders such as cancer) of Ordinance on Prevention of Dangers due to Specified Chemical Substances (hereinafter, abbreviated as “Specified Chemicals Ordinance”) of Occupational Safety and Health Act, prohibition of smoking, eating, and drinking in workplaces (Article 38-2 in Specified Chemicals Ordinance), periodic measurement of the concentration in the air (Articles 36 to 36-4 in Specified Chemicals Ordinance), installation of break rooms (Article 37 in Specified Chemicals Ordinance), and installation of washing and cleaning equipment (Article 38 in Specified Chemicals Ordinance) are obligated with respect to companies or workers using TDI or MOCA in manufacturing processes or civil engineering and construction sites.
Moreover, among Group 1 substances and Group 2 substances, carcinogenic substances or substances suspected to cause cancer are handled as specially controlled substances, and notice of names and precautions (Article 38-3 in Specified Chemicals Ordinance) and storage of records on measurement results of the concentration in the air, work operation of workers, and medical examinations for 30 years (Article 38-4 in Specified Chemicals Ordinance) are required.
In addition, an ultra-fast curing high-strength material obtained by heating an MDI-based prepolymer and DETDA separately from each other using a dedicated machine, hose-feeding the MDI-based prepolymer and DETDA to be mixed at the tip of the hose, stirring, and performing spray coating on the mixture does not have any substances that violate Specified Chemical Ordinance. However, since the dedicated machine has a large scale and mist at the time of spray coating scatters, large-scale curing or the like is required and there are many restrictions.
Since PPG that occupies a large part of the highly extensible (former Group 1) coating film waterproof material and the high-strength urethane coating film waterproof material described above has a hydrophobic methyl group (—CH2) and a hydrophilic ether group (—O—) in the main chain thereof, the solubility parameter (SP) value is calculated as 12.0 (molecular weight: 1,000, functional group: 2.0).
As the plasticizer used in the urethane coating film waterproof material, an agent which is not reacted with isocyanate (NCO group) in a main agent such as dibutyl phthalate (9.41), diheptyl phthalate (9.0), dioctyl phthalate (8.90), butyl benzyl phthalate (9.86), dioctyl adipate (8.50), chlorinated paraffin (9.21), or tris-β-chloropropyl phosphate and is highly effective for decreasing the viscosity is used. Further, the numbers in parentheses are SP values.
The highly extensible urethane coating film waterproof material (former Group 1) has a large amount of extender pigment as a filler and the filler absorbs a plasticizer. For this reason, the highly extensible urethane coating film waterproof material has a large amount of plasticizer made by adding the amount of the filler being absorbed to the amount of a plasticizer for obtaining the effect for decreasing viscosity. Meanwhile, since the high-strength urethane coating film waterproof material does not have a filler, the high-strength urethane coating film waterproof material has a small amount of plasticizer to a level in which the effect for decreasing viscosity is obtained and the volume ratio is matched.
The urethane coating film waterproof material becomes a waterproof layer after coating, but the waterproof layer is coated with a finish coating material (top coat) in addition to the highly extensible coating film waterproof material (former Group 1) and the high-strength coating film waterproof material for protecting the waterproof layer from solar radiation when used outdoors. As the kind of the top coat, a material including an acrylic urethane resin as a main component, a material including an acrylic silicon resin as a main component, a material including a fluorine resin as a main component. In addition, there are a strong solvent type material, a weak solvent type material, and a water-based type material in each top coat material. Regardless of the kind of the top coat, Durability Committee of Architectural Institute has reported that degradation of the top coat becomes faster in a case where the top coat is used on the waterproof layer formed of the highly extensible coating film waterproof material (former Group 1).
Moreover, examples of the oldest asphalt as a waterproof material include natural asphalt and vacuum residue asphalt of crude oil. These kinds of asphalt are asphalt whose softening point is set to be high in air at a high temperature and which almost do not flow at room temperature and are used for paving of roads or the like.
Further, polymer hydrocarbons, which are referred to as asphaltene, are colloidally dispersed in a Maltene compound in the asphalt. The asphaltene is a polymer compound generated by aromatic hydrocarbon of a condensed ring being cross-linked using a component that is insoluble in light hydrocarbon such as hexane, and the Maltene compound is a component containing a resin, which is soluble in light hydrocarbon such as hexane, and oil.
In this manner, since the component contents of the asphalt are complicated and the components and the ratios are different depending on locality, the SP value cannot be calculated. However, it is assumed that the SP value of the asphaltene is in the range of 9.0 to 10.0 and the SP value of the Maltene component is approximately 8.0. These SP values are close to the SP value of the plasticizer used in the urethane coating film waterproof material and the compatibility with the plasticizer is high.
At the time of repairing waterproof asphalt or the like, even when the foundation of the asphalt is directly coated with the urethane coating film waterproof material, they are not adhered to each other. When the foundation thereof is coated with the highly extensible urethane coating film waterproof material (former Group 1) after the foundation thereof is coated with a general-purpose TDI-based primer, adhesion force can be obtained, but a low fraction of asphalt migrates to the urethane coating film waterproof material (former Group 1). The migration cannot be suppressed even when a top coat is applied, the low fraction is discolored after migrating to the top coat, and degradation of the top coat is promoted.
Here, a urethane coating film waterproof material which has work efficiency that is the same as that of a general-purpose highly extensible urethane coating film waterproof material (former Group 1), an elongation rate of the highly extensible urethane coating film waterproof material (former Group 1), and physical strength the same as the strength of the high-strength urethane coating film waterproof material, does not cause a decrease in weather resistance of a top coat resulting from a plasticizer, is not affected by migration of a low fraction of asphalt, does not use TDI or MOCA of a specific chemical substance, and has high water resistance and hot water resistance has been desired.